Ngaopitakkul, Atthapol

Preferred name

Alternative Name

Ngaopitakkul, A.

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School of Engineering

atthapol.ng@kmitl.ac.th

Now showing 1 - 10 of 201

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Switching angle design for pulse width modulation AC voltage controller using genetic algorithm and distributed artificial neural network
(2011-07-26)
Jitta, Pattaraporn
;
Kaitwanidvilai, Somyot
;
Ngaopitakkul, Atthapol
This paper proposes a technique to design the switching angles in a PWM AC voltage controller using genetic algorithms (GA) and distributed artificial neural network (ANN). In the proposed technique, GA is used to evaluate the turn on and turn off angles of PWM pattern to reduce the low order harmonic content in PWM output voltage. The results from GA are then used to train the distributed ANN. The advantages gained from the proposed technique are the reduction of complexity of training process and the improvement of the ability of the ANN. In addition, the total harmonic distortion of voltage, which calculated from the low order harmonic content, is adopted in the proposed fitness function. Thus, the load value is not necessary to be known before stating the proposed technique. Simulation results show that the proposed technique is superior to the conventional fixed-duration pulse technique.
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Classification of Capacitor Bank Switching Using Fuzzy Interference Systems in 230 kV Substation
(2024-01-01)
Patcharoen, Theerasak
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Pothisarn, Chaichan
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Ngaopitakkul, Atthapol
;
Ananwattanaporn, Santipont
;
Lertwanitrot, Praikanok
Flexible AC transmission systems are used for enhancing the stability, transmission efficiency, and reliability of AC grids. Additionally, the most cost-effective devices for compensating reactive power are Mechanically Switched Capacitors (MSCs). This study proposes a novel algorithm for detection and capacitor bank switching transient signals in MSC, to prevent the protective relay maloperation by these transients. The Discrete wavelet transform (DWT) is used for effective time-frequency analysis and detection of measured three-phase current signals. DWT extracts the detailed wavelet coefficients of current signals at levels 1 to 30. In addition, the fuzzy inference system (FIS) has been used to determine the type of switching transient. The proposed combination of FIS and DWT has been tested on 230 kV substation and the result demonstrated precision for the identification and classification of both transient signals in MSC with 88% accuracy rate.
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SOH- and Temperature-Aware Adaptive SOC Boundaries for Second-Life Li-Ion Batteries in Off-Grid PV–BESSs
(2026-02-01)
Wang, Hongyan
;
Ngaopitakkul, Atthapol
;
Yoomak, Suntiti
In this study, an adaptive state-of-charge (SOC) boundary strategy (ASBS) is proposed that dynamically adjusts the admissible upper and lower SOC limits of second-life lithium-ion batteries in off-grid photovoltaic battery energy storage systems (PV-BESSs) based on real-time state of health (SOH) and temperature feedback. The strategy is formulated using a unified electrical–thermal–aging model with an online state estimator and ensures both electrical safety and power feasibility while remaining fully compatible with standard energy management functions. Two representative simulations—a single-day operating profile and a continuous thirty-day sequence—demonstrate the effectiveness of the ASBS. In the twenty-four-hour case, the duration spent in high state-of-charge conditions is reduced by approximately 0.30–0.50 h, the abrupt end-of-charging transition is eliminated, and the temperature rise is slightly moderated, all without any loss of energy supply. Over thirty days, the difference between the ASBS and a fixed state-of-charge window remains effectively zero for almost all hours, with only a brief midday deviation of −4 to −5 percentage points and no cumulative drift. Indicators of electrical and thermal stress improve substantially, including an approximate 70% reduction in the root mean square charging current. These results confirm that the ASBS provides a practical and non-intrusive means of mitigating stress on second-life lithium-ion batteries while preserving full energy autonomy in off-grid photovoltaic systems.
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A new directional relay algorithm for the protection of transmission network systems using discrete wavelet transforms
(2010-12-01)
Ngaopitakkul, A.
;
Kaitwanidvilai, S.
This paper proposes a novel directional relay algorithm to protect transmission network systems with an application of discrete wavelet transform (DWT). The fault signals are simulated using PSCAD/EMTDC. The coefficients of the positive sequence current obtained from each bus are compared in order to identify the direction of fault signals. The coefficient ratio between buses that the fault occurred is calculated so that the proper protective relay sequence can be selected. The result is shown that the algorithm is capable of performing the fault detection as well as arranging the protective relay sequence, with accurate results. ©2010 IEEE.
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Coefficient comparison technique of discrete wavelet transform for discriminating between external short circuit and internal winding fault in power transformer
(2012-01-01)
Pothisarn, C.
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Jettanasen, C.
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Klomjit, J.
;
Ngaopitakkul, A.
This paper proposes a technique for detecting and identifying internal winding fault of three-phase two-winding transformer which variations of coefficients of high frequency component obtained from DWT of differential current are analyzed. The maximum coefficient details of DWT are performed as comparison indicator in order to discriminate between internal fault and external short circuit. Various cases based on Thailand electricity transmission and distribution systems are studied to verify the validity of the proposed algorithm. Results show that the proposed technique has good accuracy to detect fault and to identify its position in the considered system.
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Study of characteristics for simultaneous faults in electrical power systems based on wavelet transform
(2010-12-01)
Ngaopitakkul, Atthapol
;
Apisit, Chaowat
In the literature for fault detection, most of research works have never been mentioned about effects of simultaneous faults. This paper presents behaviour of characteristics for simultaneous fault signals in a 500-kV electrical power transmission system using wavelet transform. The fault signal is simulated using PSCAD/EMTDC and the behavior analysis of signals is performed using discrete wavelet transform (DWT). The DWT is used in order to detect the high frequency components. The results obtained from the analysis will be useful in the development of a detect fault scheme for electrical transmission line in the future due to an effect of the other fault that occurs at the other side of the system (bus NCO) leading to the malfunction of the protective relays.
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Comparison of artificial intelligence methods for fault classification of the 115-kv hybrid transmission system
(2020-06-01)
Klomjit, Jittiphong
;
Ngaopitakkul, Atthapol
This research proposes a comparison study on different artificial intelligence (AI) methods for classifying faults in hybrid transmission line systems. The 115-kV hybrid transmission line in the Provincial Electricity Authority (PEA-Thailand) system, which is a single circuit single conductor transmission line, is studied. Fault signals in the transmission line were generated by the EMTP/ATPDraw software. Various factors such as fault location, type, and angle were considered. Then, fault signals were analyzed by coefficient details on the first scale of the discrete wavelet transform. Daubechies mother wavelet from MATLAB software was used to decompose the fault signal. The coefficient value of the mother wavelet behaved depending on the position, inception of fault angle, and fault type. AI methods including probabilistic neural networks (PNNs), back-propagation neural networks (BPNNs), and support vector machine (SVM) were used to identify faults. AI input used the maximum first peak coefficients of phase ABC and zero sequence. The results obtained from the study were found to be satisfactory with all AI methodologies having an average accuracy of more than 98% in the case study. However, the SVM technique can provide more accurate results than the PNN and BPNN techniques with less computation burden. Thus, it is suitable for being applied to actual protection systems.
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Effects of Conditional Changes on High-Voltage Direct Current Transmission Line Characteristic
(2022-01-01)
Pothisarn, Chaichan
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Ngaopitakkul, Atthapol
;
Leelajindakrairerk, Monthon
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Phannil, Natthanon
;
Bunjongjit, Sulee
The high-voltage direct current (HVDC) transmission system, which links the Gurun Substation of the National Electric Authority of Malaysia (Tenaga Nasional Berhad, TNB) with the Khlong Ngae Station of the Electricity Generating Authority of Thailand (EGAT), has been extensively researched to achieve the highest quality because it is the largest of its kind in Thailand, and there is a plant to expand its transmission power. However, the impact on the whole system is under-researched. To study and develop this system, the HVDC transmission line is modelled with the MATLAB/Simulink program and a laboratory setup to investigate the effect of transmission line distance, load power, and voltage on power loss, voltage drop, and waveform. The HVDC transmission line parameters are calculated from the actual transmission line parameters and converted to the simulation model parameters using the per-unit method. The model is verified and tested by the simulation program before creating the experimental setup. The simulation and experimental results demonstrate the effects of changing system conditions via the three aspects. All the three conditions directly affect the HVDC transmission line; nevertheless, they affect each aspect differently.
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A phase diagram approach to the detection and location of faulty capacitor units in A 115-kV capacitor bank based on unbalanced current arguments
(2023-03-01)
Pothisarn, Chaichan
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Lertwanitrot, Praikanok
;
Ngaopitakkul, Atthapol
The protection of traditional high voltage capacitor banks relies on an unbalance relay which operates when an internal fuse is blown. However, the unbalance relay cannot indicate cause or position of the fault. Thus, an operator wastes time and human resources investigating the fault issues. To address this issue, a method to locate the fault position in a capacitor bank is developed in this study. The study was simulated by using PSCAD software and modeled on the 115-kV system of the Electricity Generating Authority of Thailand (EGAT). Case studies involving faults with varied phases, side and branch connections, row connections, and inception angles were considered. Moreover, the magnitude and argument of the current phase and unbalanced current were analyzed to identify the fault location in a capacitor bank. The performance of the proposed method was verified via comparison with that of traditional methods and the results of laboratory experiments. In addition, various voltage systems were observed to verify the flexibility and accuracy of the proposed method. The results demonstrate that the proposed method was more efficient than traditional methods at locating the fault position in a capacitor bank.
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Design and application of daylight-based lighting controller on LED luminaire
(2020-05-01)
Bunjongjit, Sulee
;
Ananwattanaporn, Santipont
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Ngaopitakkul, Atthapol
;
Jettanasen, Chaiyan
;
Patcharoen, Theerasak
This paper proposes a control circuit for Light Emitting Diode (LED) luminaire based on the amount of daylight. This system uses both natural daylight and artificial light from a luminaire to reach the desired illuminance on a working plane. The control circuit operates by receiving an illuminance value from a light sensor and comparing it with a set value in the microcontroller before limiting the light intensity of LED by sending a control Pulse Width Modulation (PWM) signal to the LED driver. In the experimental setup, the controller and a physical model of a working space were built in order to field test the LED daylight control circuit. Electrical characteristics such as voltage, current, and power were measured with a power meter. Illumination characteristics in terms of illuminance on a working plane were determined using a lux meter. The results from actual field tests revealed that this LED control circuit was able to reduce the power consumption of the lighting system while keeping the illuminance on the working plane at the standard value. Both simulation results and the actual experiment of the control circuit proved that it could be used to improve the energy efficiency of both newly installed and retrofitted lighting systems.

Ngaopitakkul, Atthapol

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